The objective of this research is to obtain sufficient sequence data on the binding proteins from the periplasmic space of gram negative bacteria to allow a detailed structure-function analysis of the proteins. This includes the determination of the primary structures of E. coli galactose and ribose binding proteins and the determination of the changes in sequence of a number of functionally defective mutants of arabinose and galactose binding proteins. Purification and preliminary structural studies on the dicarboxylic acid transporting system (the periplasmic binding protein and two cytoplasmic membrane proteins) will be initiated. This information, together with the sequence and x-ray structure of arabinose binding protein already completed and that of the galactose binding protein in progress should lead to an understanding of how these molecules interact with the membrane-bound constituents of these transport systems and facilitate transport of the nutrients.